KR20100008161A - Thermal oxidation reactor for automatic measurement of nitrogen and phosphorous - Google Patents

Abstract

PURPOSE: A thermal oxidation reactor for automatic measurement of nitrogen and phosphorous is provided to reduce the time for lowering the temperature after oxidization and thereby shorten the time for analysis. CONSTITUTION: A thermal oxidation reactor for automatic measurement of nitrogen and phosphorous is as follows. In order to heat and oxidize a sample at 120°C for 30 minutes, an aluminum block(10) is made by processing an aluminum ingot into a cylindrical shape. The aluminium block is punched and a glass tube(4) and a heating element(13) are fitted into the hole, thereby achieving uniform heating. The aluminium block at the boundary in contact with the glass tube is spirally carved to form a cooling coil(3) in which cooling water flows.

Description

Thermal Oxidation Reactor for Automatic Measurement of Nitrogen and Phosphorous

1 is a schematic diagram of a heating oxidation reactor according to the present invention

* Explanation of symbols for main parts of the drawings

1: upper cap, 2: coolant inlet solenoid valve, 3: cooling coil, 4: glass tube 5: temperature sensor for temperature control, 6: cooling water discharge line, 7: lower cap, 8: lower solenoid valve, 9: temperature sensor for preventing overheating, 10: aluminum block, 11: insulation, 12: outer case, 13: heating element, 14: O-ring, 15: upper solenoid valve

The present invention relates to a thermal oxidation reactor used for the automatic analysis of total nitrogen and total phosphorus. Nitrogen is present in the form of organic nitrogen, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen. Phosphorus also exists in the form of organic phosphorus, condensed phosphorus, phosphorus phosphorus and the like. Therefore, in the case of total nitrogen contained in water, it is oxidized in the form of nitrate nitrogen, and then absorbance is measured in ultraviolet light of 220 nanometers. Quantify

In the method of measuring total nitrogen and total phosphorus specified in the Korea Water Pollution Process Test Method, the oxidation method is explained. It is.

Heating is to use a high pressure steam sterilizer. Therefore, the sample is placed in a glass bottle or a fluororesin-type bottle and oxidized in a high-temperature steam autoclave.

However, in the case of automatic analysis, a normal autoclave cannot be used because the sample is automatically injected and withdrawn. Therefore, various types of oxidation reactors have been developed for automatic analysis. The most important thing in the automatic analytical oxidation reactor is that the oxidation result of the sample should be consistent with that of the autoclave according to the water pollution process test method. However, due to the nature of the automatic analyzer, it cannot be heated and oxidized in a high-pressure steam sterilizer like the water pollution process test method. The main reason for the difference in oxidation rate is that there is a difference between the oxidation mechanism of the oxidation reactor for the automatic analyzer and the oxidation mechanism of the oxidation reaction in the water pollution process test method. In addition to the oxidation reaction, the automated analysis requires various processes such as sample transfer, chemical injection, reaction, and mixing. Therefore, in order to reduce the analysis time, it is necessary to reduce the time required for each process as much as possible.

According to Japanese Patent Laid-Open No. 2001-83136, an aluminum block is wrapped with a heating element, an ultraviolet lamp is placed on both sides of the inside of the aluminum block, and a glass tube-shaped reactor is placed in the center of the aluminum block. Ultraviolet rays are irradiated while raising the temperature to 100 degrees Celsius, inducing an oxidation reaction by heating and ultraviolet irradiation.

In addition, an electrode is placed inside the glass tube to induce an oxidation effect by electrolysis. In the case of the present invention, three oxidation mechanisms are introduced to induce a certain oxidation reaction, but the apparatus is very complicated and a failure factor is also increased. In addition, it has an oxidation mechanism different from that of the water pollution process test method, and thus, a result different from that of the water pollution process test method is often obtained depending on the properties of the measurement sample.

According to Japanese Patent Laid-Open No. 2004-93509, a glass tube is twisted in a spiral to be used as a reactor. The glass tube is wrapped around the heating element and heated. This invention has an oxidation mechanism similar to that of the water pollution process test. However, it takes a long time to cool the heated sample to room temperature, which increases the analysis time. In addition, a glass tube with low heat transfer efficiency is used. Since the heat transfer medium is air, uniform heating is difficult.

In the present invention, when the sample is oxidized to automatically measure total nitrogen and total phosphorus, heat is uniformly and quickly transferred to the sample, heating and cooling are performed in one reactor, rapid cooling rate, and oxidation of the water pollution process test method. The present invention provides a heated oxidation reactor having the same oxidation rate as that of the high pressure steam sterilizer.

In the present invention, to increase the temperature of the reactor as quickly as possible and also to cool quickly after the reaction. As shown in FIG. 1, the aluminum ingot 10 is manufactured by machining the aluminum ingot having a good heat transfer into a cylindrical shape. A hole is drilled into the aluminum block 10 to insert the heating element 13 and the glass tube 4 as a reaction tube. At this time, the heat generating element 13 and the glass tube 4 are in close contact with the aluminum block 10 so that the heat of the heat generating element 13 is uniformly and quickly transmitted to the glass tube 4 through the aluminum block 10. Glass tube 4 was used as the reaction tube, but a metal material or heat-resistant plastic may be used.

As mentioned above, the automatic measuring device requires various processes such as chemical injection, color development, absorbance measurement as well as oxidation reaction. Therefore, it is important to save as much time as possible in each process. In the present invention, in order to increase the cooling rate, the glass tube 4 is inserted into the aluminum block 10 to form a cooling coil 3 by making a spiral groove from the top to the bottom.

The cooling water inlet pipe and the cooling water discharge pipe 6 are connected to this groove. The coolant inlet solenoid valve 2 is connected to the coolant inlet tube. When the reaction is completed at 120 degrees Celsius, the coolant inlet solenoid valve (2) is opened and the coolant is introduced. The introduced cooling water flows down along the cooling coil 3 of the aluminum block 10, and is in direct contact with the glass tube 5. Therefore, the cooling rate is very fast. Cooling water can be directly connected to tap water or can be injected using a pump. When the cooling water is directly connected to the tap water, it is necessary to adjust the pressure of the cooling water by attaching a pressure regulating valve. Although the cooling time was somewhat different depending on the pressure of the cooling water, if the amount of cooling water flowed more than 1.3 liters per minute, the cooling time was not significantly different. When cooling water flowed over 1.3 liters per minute, it was confirmed that the samples at 120 degrees Celsius were cooled to 30 degrees Celsius or less within 1 minute.

The upper cap 1 and the lower cap 7 are fitted in the glass tube 5 at the upper part and the lower part. Since these caps are firmly fixed by the outer case 12, the airtightness inside the glass tube 4 can be maintained even when it heats. O-rings 14 were fitted to each cap to improve airtightness.

In the temperature sensor, a temperature sensor 5 for controlling temperature and a temperature sensor 9 for preventing overheating are inserted into the aluminum block 10. Temperature control temperature sensor is a sensor for controlling the temperature of the reactor. The overheat prevention temperature sensor 9 has a function of sounding an alarm when a failure of the heating element 13 or a failure of the temperature control temperature sensor 5 occurs due to overheating or a temperature rise schedule does not match. Around the aluminum block 10, the ceramic fiber insulation 11 was surrounded and insulated, and the outside was covered with an aluminum case to increase safety.

The pretreatment of the sample is as follows. The upper solenoid valve 15 and the lower solenoid valve 8 attached to the glass tube 4 are opened and a sample is injected through the lower solenoid valve 8 using a pump. When sample injection is completed, the upper solenoid valve 15 and the lower solenoid valve 8 are closed. Next, using a heating element 13 and the temperature control temperature sensor 5, the temperature is raised to 120 degrees Celsius and reacted for 30 minutes. The time to reach 120 degrees Celsius varies depending on the reaction start temperature, but reaches 8 degrees to 10 degrees Celsius. After the reaction, the valve of the cooling water inlet solenoid valve 2 is opened to flow the cooling water to the cooling coil 3 of the aluminum block 10. When the temperature is cooled to room temperature, the coolant inlet solenoid valve 20 is closed. Next, the upper solenoid valve 15 and the lower solenoid valve 8 are opened, and the pump is rotated in reverse to take out the sample. The lower solenoid valve 8 may use a three-way solenoid valve. In this case, the sample is injected in one direction and the sample is taken out in the other direction.

When the result of oxidizing the sample using the present invention and the result of oxidizing by pretreatment according to the water pollution process test method had a range of 98 to 101 percent with respect to the amount of oxidation by the water pollution process test method. It was found that it had the same level of oxidation power as the pretreatment method of the water pollution process test method.

When the present invention is used to measure total nitrogen and total phosphorus, it is possible to greatly reduce the time required for analysis by heating to 120 degrees Celsius and oxidizing the reaction to cool to room temperature. In addition, compared with the pretreatment method of the water pollution process test method, it shows the same oxidation power, enabling accurate analysis. The heating oxidation reactor of the present invention can be widely used in various automatic measuring devices and oxidation reactors.

Example 1

Oxidation experiments for total nitrogen measurement were carried out using the heat oxidation reactor of the present invention. Urea was dissolved in pure water to bring the total nitrogen to 2 ppm (ppm). 2 milliliters of potassium persulfate solution and 2 milliliters of caustic soda solution were added to 30 milliliters of this sample, and a sample was injected into the glass tube 4 using a pump from the bottom of the reactor. The amount and composition of the chemical added to the sample was adjusted according to the amount of sample water according to the water pollution process test method. The temperature of the thermostat was set to 120 degrees Celsius and operated for 30 minutes after reaching 120 degrees Celsius.

After the reaction, the mixture was cooled by flowing cooling water until it reached 30 degrees Celsius or less. After cooling, the sample was taken out and the absorbance was measured at a wavelength of 220 nanometers using a spectrophotometer. The same sample was pretreated according to the water pollution process test method and the absorbance was measured at a wavelength of 220 nanometers using a spectrophotometer. The obtained absorbance was compared with the absorbance of the sample pretreated using the oxidation reactor of the present invention. In addition, the time reached to 120 degrees Celsius, the time cooled to the start temperature was measured. The same test was repeated 10 times and the results are shown in Table 1.

Table 1. Oxidation Experiment Results of Example 1

Example 2

Oxidation experiment for total phosphorus measurement was carried out using the heat oxidation reactor of the present invention. Disodium phenylate was dissolved in pure water so that the total phosphorus concentration was 1 ppm. 2 milliliters of potassium persulfate solution was added to 30 milliliters of this sample, and the sample was injected into the glass tube 4 using the pump from the bottom of a reactor. The amount and composition of the chemical added to the sample was adjusted according to the amount of sample water according to the water pollution process test method. The temperature of the thermostat was set to 120 degrees Celsius and operated for 30 minutes after reaching 120 degrees Celsius. After the reaction, the mixture was cooled by flowing cooling water until it reached 30 degrees Celsius or less. After cooling, the sample was taken out, 2 milliliters of ammonium molybdate ascorbic acid mixture was added thereto, and reacted for 10 minutes. The absorbance was measured at a wavelength of 880 nanometers using a spectrophotometer. The same sample was pretreated according to the water pollution process test method, and the absorbance was measured at a wavelength of 880 nanometers using a spectrophotometer. The obtained absorbance was compared with the absorbance of the sample pretreated using the oxidation reactor of the present invention. In addition, the time reached to 120 degrees Celsius, the time cooled to the start temperature was measured. The same test was repeated 10 times and the results are shown in Table 2.

Table 2. Results of Oxidation Experiment of Example 2

Claims (2)

In order to measure total nitrogen and total phosphorus automatically, the aluminum ingot is processed into a cylindrical block to heat and oxidize the sample by heating at 120 degrees Celsius for 30 minutes, and the aluminum block is made by making a hole in the block. Heated oxidation reactor to make heating uniform by inserting The heating oxidation reactor according to claim 1, wherein a cooling coil is formed by spirally circulating the aluminum block at the interface where the glass tube, which is the reaction tube, and the aluminum block contact each other in order to increase the cooling rate of the reactor.

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